Question

Estimate the number of electrons in $100g$ of water. How much is the total negative charge on these electrons?

Answer 1

No. of molesof $100$g water

$=\frac{100}{18}=5.55$ moles

The total charge is due to the number of electrons. One molecule contains 10 electrons.

No. of electrons in $18$g of $H_{2}O$

$n=6.023\times {10}^{23}\times 10=6.023\times {10}^{24}$

No. of electrons in $100$g of $H_{2}O$

$=\frac{6.023\times {10}^{-24}\times 100}{18}=0.334\times {10}^{25}=3.334\times {10}^{25}$

Total charge will be

$q=3.34\times {10}^{25}\times 1.6\times {10}^{-19}$

$=5.34\times {10}^6$c.